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Block Move Instructions 6-5
Figure 6.1 SCRIPTS Overview
6.3 Block Move Instructions
The Block Move SCRIPTS instruction is used to move data between the
SCSI bus and memory. For a Block Move instruction, the LSI53C810A
operates much like a chaining DMA device with a SCSI controller
attached. Figure 6.2 illustrates the register bit values that represent a
Block Move instruction. In Block Move instructions, bits 5 and 4 (SIOM
and DIOM) in the DMA Mode (DMODE) register determine whether the
source/destination address resides in memory or I/O space. When data
is being moved onto the SCSI bus, SIOM controls whether that data
comes from I/O or memory space. When data is being moved off of the
SCSI bus, DIOM controls whether that data goes to I/O or memory
space.
System Processor
System Memory
SCSI Initiator Write Example
× Select ATN 0, alt_addr
× Move from identify_msg_buf, when MSG_OUT
× Move from cmd_buf, when CMD
× Move from data_buf when DATA_OUT
× Move from stat_in_buf, when STATUS
× Move from msg_in_buf, when MSG_IN
× Move SCNTL2 & 7F to SCNTL2
× Clear ACK
× Wail disconnect alt2
× Int 10
S
Y
S
T
E
M
Write DSP
Fetch
SCRIPTS
Data
LSI53C810A
SCSI Bus
B
U
S
Data Structure
Message Buffer
Command Buffer
Data Buffer
Status Buffer